Exercise can reverse damage to sedentary, ageing hearts and help prevent risk of future heart failure -- if it's enough exercise, and if it's begun in time, according to a new study by cardiologists.
To reap the most benefit, the exercise regimen should begin before age 65, when the heart apparently retains some plasticity and ability to remodel itself, according to the findings by researchers at the Institute for Exercise and Environmental Medicine (IEEM), Dallas.
And the exercise needs to be performed four to five times a week. Two to three times a week was not enough, the researchers found in an earlier study.
"Based on a series of studies performed by our team over the past 5 years, this 'dose' of exercise has become my prescription for life," said senior author Dr. Benjamin Levine, Director of the Institute and Professor of Internal Medicine at UT Southwestern. "I think people should be able to do this as part of their personal hygiene -- just like brushing your teeth and taking a shower."
It included exercising four to five times a week, generally in 30-minute sessions, plus warmup and cool-down:
1) One of the weekly sessions included a high-intensity 30-minute workout, such as aerobic interval sessions in which heart rate tops 95 percent of peak rate for 4 minutes, with 3 minutes of recovery, repeated four times (a so-called "4 x 4").
2) Another day's session lasted an hour and was of moderate intensity. (As a "prescription for life," Levine said this longer session could be a fun activity such as tennis, aerobic dancing, walking, or biking.)
3) One or two other sessions were performed each week at a moderate intensity, meaning the participant would break a sweat, be a little short of breath, but still be able to carry on a conversation -- the "talk test." I
4) One or two weekly strength training sessions using weights or exercise machines were included on a separate day, or after an endurance session.
Study participants built up to those levels, beginning with three, 30-minute, moderate exercise sessions for the first 3 months and peaked at 10 months when two high-intensity aerobic intervals were added.
The more than 50 participants in the study were divided into two groups, one of which received two years of supervised exercise training and the other group, a control group, which participated in yoga and balance training.
At the end of the two-year study, those who had exercised showed an 18 percent improvement in their maximum oxygen intake during exercise and a more than 25 percent improvement in compliance, or elasticity, of the left ventricular muscle of the heart, Dr. Levine noted.
He compared the change in the heart to a stretchy, new rubber band versus one that has gotten stiff sitting in a drawer.
Sedentary aging can lead to a stiffening of the muscle in the heart's left ventricle, the chamber that pumps oxygen-rich blood back out to the body, he explained.
"When the muscle stiffens, you get high pressure and the heart chamber doesn't fill as well with blood. In its most severe form, blood can back up into the lungs. That's when heart failure develops," said Dr. Levine.
Erin J. Howden, Satyam Sarma, Justin S. Lawley, Mildred Opondo, William Cornwell, Douglas Stoller, Marcus A. Urey, Beverley Adams-Huet, Benjamin D. Levine. Reversing the Cardiac Effects of Sedentary Aging in Middle Age—A Randomized Controlled Trial: Implications For Heart Failure Prevention. Circulation, 2018; CIRCULATIONAHA.117.030617 DOI: 10.1161/CIRCULATIONAHA.117.030617
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Scientists have created tiny artificial human muscles that contract and respond to neural and electrical stimuli just like real muscles do, a new study reports.
THERE'S JUST ONE TWIST: The functioning muscle fibres were made from Skin cells, not Muscle cells.
The successful experiment, detailed in an article published yesterday (Jan. 9) in the journal Nature Communications, could help researchers better study genetic muscular dystrophies, and test new treatments.
In the study, the researchers began by taking cells from skin samples from humans. They used a known technique to turn these cells into so-called induced pluripotent stem cells — cells that can transform into any type of human cell.
Then, using a new method they developed, the scientists were able to turn these pluripotent stem cells into muscle stem cells, which are called myogenic progenitors.
Nenad Bursac, a professor of biomedical engineering at Duke University in North Carolina said "It takes about three weeks until they become reprogrammed."
Using just one pluripotent stem cell taken from a donor, the researchers can create thousands of muscle stem cells. This is because once turned into muscle stem cells, these cells can multiply further.
Then, the muscle cells were placed in a 3D culture that contained various nutrients and growth factors that stimulate the cells to organise into muscle fibres.
After another three weeks, pieces of muscle tissue up to 2 centimeters (0.8 inches) long, almost 1 millimeter (0.004 inches) in diameter, formed in the solution.
WHO NEEDS NEW MUSCLES?
The development could significantly improve study of genetic muscular diseases, such as Duchenne Muscular Dystrophy, which affects 1in 3,600 male infants worldwide.
People with Duchenne Muscular Dystrophy start having muscle weakness at about age 4. The condition quickly progresses and by age 12, the patients lose their ability to walk. Most die by age 26.
Since the fibers that the scientists created in the study are fully functioning, the researchers can now study how they respond to various treatments, Bursac said.
He hopes the technique could be used in the future to re-engineer a patient's damaged cells into healthy cells and use the resulting muscle fibers to improve the patient's quality of life.